SKU: 63299332735

Ronstan Series 55 Ball Bearing Orbit Block™ - Single - Becket - Swivel Head

Sale price$45.52 Regular price$50.58
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Description

Ronstan Series 55 Ball Bearing Orbit Block™ - Single - Becket - Swivel HeadSeries 55 Ball Bearing Orbit Block Single Becket Swivel Head Lightweight Kilogram for kilogram of working load, BB and RT Orbit Blocks are the world's lightest. The unique orbital design allows the bearing to only be in the active areas of the floating sheave. This minimises the mass of the inactive return race and hub. Weight and bulk are further reduced in the different block configurations. The ball bearing single and becket block has a through

Series 55 Ball Bearing Orbit Block™ - Single - Becket - Swivel Head

Lightweight
Kilogram for kilogram of working load, BB and RT Orbit Blocks™ are the world's lightest. The unique orbital design allows the bearing to only be in the active areas of the floating sheave. This minimises the mass of the inactive return race and hub.

Weight and bulk are further reduced in the different block configurations. The ball bearing single and becket block has a through-sheave becket arrangement. The result? The lowest weight possible.

Multi-sheave blocks have only single intermediate cheeks and an ultra-light and efficient head arrangement. This gives a 30% weight saving advantage over the nearest competitor. Other brands just link together their single blocks. This results in unnecessary double cheeks between each sheave, held together by a heavy steel channel across the top of the block.

Highest Working Load In Its Class
The orbital ball-bearing arrangement gives the largest possible bearing race diameter. This maximises load performance. The proven Ronstan 2-stage bearing system features high compression grade acetal ball bearings and a secondary full-contact bearing. This gives minimum friction across the full working load range.

The floating sheave and bearing system is supported by a fiber-reinforced load frame. The design was computer modelled to be stress optimised. The Dyneema® Link is produced from FSE Robline SK75 fiber, which is 10 times stronger and lighter than steel, and provides the final connection from the block to the load point.

Features:
  • Ultra Lightweight
  • Low friction 2-stage Orbital ball bearing system
  • Highest working load in its class
  • Low profile and compact
  • High performance cleating
  • Swivel shackle head for unlimited block rotation
  • Stainless steel shackle head for ultimate durability and compatibility with harsh fixing points
  • Ultra low profile integrated becket


Applications:
  • Mainsheet systems on dinghies, sportsboats and small keelboats to 9M(30')
  • Spinnaker sheets on dinghies, sportsboats and small keel boats to 9M(30')
  • Halyard, Vang and Backstay application on boats to 8M(26')
  • Control line applications on larger yachts
  • Ideal use for mainsheet systems and spinnaker sheets on dinghies, sportsboats and small keel boats to 9M(30')
  • Also ideal with halyard, vang and backstay applications on boats to 8M(26')
  • Spinnaker sheets on sportsboats and small keel boats (lateral lead blocks)
  • Control line applications on larger yachts


Materials:
  • Ball bearings - High compression strength carbon black Acetal
  • Stage 2 bearing - Carbon fiber reinforced, PTFE impregnated Nylon
  • Frame/Cheeks - Toughened, glass fiber reinforced Nylon
  • Rope Link: UV stabilized, multi-strand impregmented SK75 Dyneema®
  • Sheave: Carbon fiber reinforced, PTFE impregnated Nylon
  • Head fitting: Grade 316 stainless steel.


Specifications:
Sheave Ø: 55mm(2-5/32")
Max. Rope Ø: 10mm(3/8")
M.W.L.: 500kg(1,100lbs)
B. L.: 1,000kg(2,200lbs)
Weight: 88g(3.1oz)
Manufacturer : Ronstan
Manufacturer Part No : RF55110
UPC : 9316800440405
Shipping Notes
  • Free Standard Shipping on $100+ Orders to the USA.
  • Except Preorder products are shipped in 48 hours.
  • Delivery to the USA:
  1. Standard Shipping : 3-10 business days
  • If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
  • We offer a 30-day return/exchange service after receiving.
  • Final sale items are not eligible for returns or exchanges.
  • To process your return/exchange, please contact us at [email protected]
  • Please click here for more details>>> Return & Exchange Policy
SKU: 63299332735

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4.1 ★★★★★
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SeanCeltiad
Lowell, US
★★★★★ 4
A true turtleneck that retains a snug high neck.
Color: White, Size: X-Large
I've found this brand to have gotten better over the years as far as offering the American market what it needs in terms of realistic sizing. I only wish they'd realize that there are a lot of us who are long in the back and arms where my only choice is to go a size up and sacrifice a slim fit for sleeves that are long enough plus a back that doesn't go up past my waist just because I reach up for something, that and I like to be warm. So these are such nice quality turtlenecks that it's hard to complain about but maybe the company will read this. The snug neck stays up is plus number one since that's why I'm buying a full neck. They come with very nice weaves in the fabric, good enough for casual or formal wear. Finally the warmth you seek is there but I've worn them in what most would think isn't the right temp for a turtleneck. Also they have them in white! Yes, a lot of others just don't for reasons I can't fathom, and the pic you're seeing is accurate, these will form to your shape without being ridiculously thin material. Several washes later and they are as fine a garment as when I first wore them. I've only found one other brand that compares to these but it's much more expensive, COOFANDY is affordable in these times of expensive everything. Warm but also a lightweight shirt, I've gotten them really dirty with actual dirt and it washes out so well you'd never know it. Don't let my taking off one star stop you, try one yourself and you'll be coming back for more.
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Reviewed in the United States on July 30, 2025
L
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Larry
Natrona Heights, US
★★★★★ 5
Quality,warmth and fit
Color: Royal Blue, Size: Small
Really top quality. This is my 4th purchase of these Really great sweaters.
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Reviewed in the United States on February 12, 2026
R
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Robert III
New York, US
★★★★★ 5
Nice Sweater
Color: 01-black, Size: Large
This is a very nice sweater. It’s reasonably thick and warm. Looks nice. I like it.
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Reviewed in the United States on January 18, 2026
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Tajuana Perkins
Bozeman, US
★★★★★ 5
Nice turtle neck sweater
Color: Royal Blue, Size: Small
It was true to size a perfect fit and the color is beautiful. Nice sweater for the amount paid.
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Reviewed in the United States on January 11, 2026
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Nathalie M. Rosario Escobar
Massapequa, US
★★★★★ 5
Very good
Color: 01-black, Size: Small
It looks so good on my bf, he really like it. The quality is so perfect.
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Reviewed in the United States on January 15, 2026

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